One or more aspects of the invention relate, in general, to the transfer of data to and from memory of a computing environment, and in particular, to the processing of out-of-order data transfers within the computing environment.
In some computing environments, such as those that include System z® servers offered by International Business Machines Corporation, data is transferred from memory of a computing system to input/output devices, and from the input/output devices to memory using one or more host bus adapters (HBAs). The host bus adapters are attached to the system through hardware which isolates the host bus adapters from the system. This hardware provides isolation of the unchecked host bus adapter from the system, so as to maintain reliability, availability and serviceability (RAS) for the system.
With this type of configuration, all data flowing to/from the system is temporarily stored in the hardware, and then, moved from the hardware to its intended destination. Thus, a store and forward delay is incurred for each data transfer.